1. Technical Field
The present invention relates to a measurement device capable of measuring physical quantity such as temperature and humidity.
2. Description of the Related Art
There is a system that monitors temperatures with the use of thermometers installed at appropriate intervals for the purpose of temperature control of an air conditioning system, quality maintenance of products, and the like in an office, a building, a factory, or a shop. In the past, temperatures were monitored by service persons for observing the respective thermometers installed at appropriate frequency and recording measured temperatures. Recently, in many cases, temperature-measuring units are connected to a central monitoring device via transmission cables for automatic temperature monitoring.
In a system where a large number of temperature measuring units are connected via transmission cables, connecting each of the temperature measuring units directly to a monitoring device may cause problems of insufficient monitoring device interfaces or excessive number of cables. Thus, it is necessary to reduce the number of the cables by providing a device capable of integrating a suitable number of temperature measuring units into one group and performing intermediate processing, or to connect a device capable of handling a lot of terminals such as a marshaling box to the monitoring device. As a result, even when the system is required to monitor the temperature only, it becomes complicated and high-priced to cover a wider measurement area having a large number of measuring points.
Moreover, in order to construct a system for monitoring the temperatures, it is necessary to prepare not only units for measuring the temperatures at remote ends but also plural kinds of devices, such as an intermediate processing device, or a terminal handling device and, needless to say, cables for connecting those units. Therefore, it is necessary to prepare an appropriate number of devices per each kind or purpose in addition to the measuring units depending on what kind of the building for temperature measurement or how large it is. The desired temperature measurement system can be realized only when the system design and appropriate kinds and quantities of materials are prepared in a reliable manner. Consequently, the system design is the essential factor, and the manufacturer for supplying temperature measurement systems should prepare sufficient kinds and quantities of devices other than the measuring units.
This requirement applies not only to the case for newly constructing the measurement system but also to the case for enlarging the area covered by the measurement system, changing measuring points or changing measuring system. When changing the measurement system, devices that have been used in the previous system are diverted to the new system. This results in limitation of the system configuration, failing to construct the optimum system.
This constraint or limitation applies not only to the temperature measurement system but also to other systems for measuring various types of physical quantity such as humidity, noise and amount of rainfall, by means of sensors.
Therefore, it is an object of the present invention to provide a measurement device that allows free configuration of the measurement system for collecting measured data from a large number of sampling points and facilitates change in the system using the minimum kinds of devices and/or units. Moreover, it is another object of the invention to provide a measurement device such that the manufacturer for supplying measurement systems can satisfy demands of the users in a flexible manner simply by preparing minimum kinds or types of devices and/or units.
The present invention provides a measuring device that is designed and manufactured in accordance with a single set of specifications and the measuring device employs radio communication as principle transmission/reception means of the data so as to construct the measurement system capable of collecting data through measurement devices and collecting the data acquired at respective locations. That is, the measurement device of the present invention includes a measurement portion for acquiring data from a sensor, a memory portion for storing the data, a radio portion for performing radio transmission/reception of the data, a PC interface portion for transmitting the data to a host computer via the universal interface, and a control portion for controlling the measurement portion, memory portion, radio portion, and PC interface portion. The control portion of the present measuring device has a switching function for setting a mode by selecting between a remote mode and base mode. In the remote mode, the data acquired by the measurement portion are stored in the memory portion and transmitted by the radio portion. In the base mode, the data acquired from the radio portion are stored in the memory portion and transmitted to the host computer by the PC interface portion.
Since the measurement device according to the present invention is designed to be able to send the data through radio transmission, no transmission cables or wires are required and a system for collecting data from a plurality of measuring points can easily be constructed. Further, by setting the measurement device in the remote mode, the measurement device acts as a remote unit for performing the measurement at each point. By setting the measurement device in the base (parent) mode, the measurement device acts as a base unit provided with a function of collecting data and transmitting them to the host computer for data collection via the universal interface with cable or an infrared ray interface etc. The computer serves as a monitoring device. In addition, the computer serves as an extra relay unit for covering an even wider area via a LAN.
Therefore, by adopting measurement devices of this invention designed and manufactured with a single set of specifications, installing them to the respective points, and setting each in a different mode depending on the installation point, the measurement system that obtains and collects data from a large number of points is constructed. Consequently, by using the measurement devices according to the present invention, the measurement system can be constructed in a flexible manner, eliminating problems of excess or lack in the instrument for the particular purpose as well as other materials. The system can also be readily changed. The measurement devices of a single set of specifications may allow construction of the system in conformity with the object subjected to measurement can be constructed in a configuration suited thereto.
Moreover, the manufacturer is required to simply produce measurement devices of the same kind that is designed and fabricated in accordance with a single set of specifications for the remote unit and base unit and supply them, which eliminates costs for production management or inventory management. As a result, the measurement devices can be supplied at lower costs. In addition, the manufacturer may reliably cope with user""s demand of constructing the system of various designs by simply supplying the same type or kind of the present measurement devices of a single set of specifications without partitioning remote unit and base unit.
Furthermore, the measurement device according to the present invention temporarily stores the measured data in the memory portion for data transmission/reception. Therefore the time required for the communication can be minimized and a low power consumption system can be constructed. Considering especially the case where the measurement device is set in the remote mode, it is often the case that external power sources such as a power from wall socket cannot be used. Instead the built-in battery has to be used for the measurement and transmission/reception of data. It is, thus, important to minimize the time for the data transmission/reception. In addition, intermittent operation of the radio portion may reduce power consumption of the measurement device in the remote mode.
In order to send the data to a measurement device in the base mode from the measurement devices of remote mode, a communication method having following steps is preferable: the measurement device of the base mode transmits a broadcast call that calls the measurement devices of remote mode for a period equal to or longer than an intermittent cycle, the call is received by the measurement devices of remote mode so as to synchronize timing counters of the measurement devices of remote mode; and after an end of the broadcast calling, the measurement devices of remote mode are brought into the ready to transmission/receive state in a predetermined order for transmitting the measured data to the measurement device of base mode.
Moreover, preferably the measurement device is selectively provided with a relay mode, in addition to the remote mode and the base mode, where the measured data acquired by the radio portion is stored in the memory portion and transmitted by radio portion. With this mode, even when the measurement device in the remote mode is installed in such a point that a radio wave cannot reach or hardly reach, reliable data exchange between the measurement device in the remote mode (hereinafter referred to xe2x80x9cremote-mode devicexe2x80x9d) and the measurement device in the base mode (hereinafter referred to xe2x80x9cbase-mode devicexe2x80x9d) can be established by installing the measurement device selected in the relay mode (hereinafter referred to xe2x80x9crelay-mode devicexe2x80x9d) intermediately.
The switching of the mode among base, remote and relay modes can be performed using a dipswitch or the like. However, if the switching is operable by software via the PC interface portion, it is convenient for the user because status of the switching can be confirmed on the computer. In addition, it is preferable that the control portion has identification information for transmission/reception being set by the host computer via the PC interface portion. By the identification information, the measurement devices can be given any setting freely which are to be required in constructing a highly-sophisticated, flexible measurement system, such as grouping of the remote-mode devices, assigning of a relay-mode device to each of the groups. Therefore, the present invention can provide measurement devices according to the single set of specifications that can construct the measurement system in a flexible manner at the high level.